1. Field of the Invention
The present invention relates to a power semiconductor module, and more particularly, to a power semiconductor module in which a main circuit terminal lead frame part and a control circuit lead frame part are bent toward a main circuit lead frame part.
2. Description of the Related Art
Advancement in the power electronics industry, e.g., inverters and servo drivers, triggers a need for a light and compact power system that is manufactured at a low cost and operates more efficiently. To realize such a power system, electronic components are integrated into one package, i.e., a power semiconductor module, and a large number of power devices and control integrated circuits (IC), which control the power devices, are integrated into one power semiconductor module that is capable of controlling and protecting power devices. This power semiconductor module is called an xe2x80x98intelligent power modulexe2x80x99.
FIGS. 1 through 3 are views of conventional power semiconductor modules. FIG. 1 is a view of a semiconductor package disclosed in U.S. Pat. No. 6,002,166. Referring to FIG. 1, all components (some not shown) such as a semiconductor device and a control circuit device are combined with one another by solder (not shown), and a semiconductor chip 1 attached to a lead frame (not shown) is electrically connected with a terminal 5 by a bonding wire (not shown). The size of the semiconductor package of FIG. 1 is determined according to the sizes of all components attached to the lead frame. Thus, an increase in the number of components required results in an increase in the size of the semiconductor package. As the size of the semiconductor package increases, more components, such as a substrate and a mold compound, are required in fabricating the semiconductor package, thus increasing manufacturing costs therefor. Also, in the semiconductor package, the distance between a base substrate 3, which contacts a heat sink (not shown), and a terminal 5 extended to the exterior of a mold compound 7, which molds the semiconductor package, is approximately 4-5 mm. In other words, the isolation height h, which is the distance between the terminal 5 connected to the exterior circuit and the heat sink, is about 4-5 mm. Therefore, the isolation height of the semiconductor package is lower than the UL (underwriters laboratory) standard, i.e., 12.7 mm. If the isolation height is below the UL, the electrical insulation of a semiconductor package deteriorates.
FIG. 2 is a view of a semiconductor package disclosed in U.S. Pat. No. 5,521,437. Referring to FIG. 2, all components are attached to an insulated metal substrate 16 and are electrically connected to one another by a bonding wire 18. Thus, the size of the semiconductor package is determined by the size of the insulated metal substrate 16 to which all components are attached. That is, an increase in the number of the components required results in an increase in the size of the semiconductor package. Also, as the size of the semiconductor package increases, a great number of components, such as an insulated metal substrate and a mold compound, are required in fabricating the semiconductor package, thus raising manufacturing costs therefor. In FIG. 2, reference numerals 11, 13, 15, 17 and 19 denote a case, a control circuit terminal, a main circuit terminal, a main circuit part, and a control circuit unit, respectively.
FIG. 3 is a view of a semiconductor package disclosed in U.S. Pat. No. 5,471,089. Referring to FIG. 3, a main circuit part 35 having a power semiconductor device and a control circuit part 33 including a control circuit device are formed on different substrates. The main circuit part 35 and the control circuit part 33 are installed at the top and bottom of the semiconductor package, respectively. Also, they are connected to each other by a metal connection 37. Portions of the main circuit part 35 and the control circuit part 33 that contact the metal connection 37 are soldered by a solder 32. In conclusion, in the semiconductor package shown in FIG. 3, the main circuit part 35 and the control circuit part 33 are formed on different substrates at the top and bottom of the semiconductor package. Also, the metal connection 37 and the solder 32 are indispensable in connecting the main circuit part 35 with the control circuit part 33. Accordingly, it is very difficult to realize such a semiconductor package. Here, reference numerals 31 and 39 denote a terminal and a case, respectively.
To solve the above problem, it is a first objective of the present invention to provide a light and compact power semiconductor module that is simple to manufacture at a lower cost.
It is a second objective of the present invention to provide a method of fabricating such a power semiconductor module.
Accordingly, to achieve an aspect of the first objective, there is provided a three-dimensional power semiconductor module according to an embodiment of the present invention. The power semiconductor module includes a main circuit part mounted on an isolation substrate and including a power semiconductor device; a control circuit part positioned along a plane, forming a predetermined angle to the main circuit part, the control circuit part attached to a control circuit device; a control circuit terminal connected to the control circuit part; a main circuit terminal positioned along another plane, forming a predetermined angle to the main circuit part; a bonding wire for electrically connecting the control circuit terminal, the control circuit device, the power semiconductor device, and the main circuit terminal; and a mold compound for completely molding the main circuit part and the control circuit part.
Preferably, the main control part is attached to the isolation substrate by an adhesive, and the control circuit part is positioned along a plane perpendicular to the main circuit part.
Preferably, the control circuit terminal is positioned along the same plane as the control circuit part.
Preferably, the main circuit terminal is placed along a different plane, making it symmetrical with the control circuit part with reference to the main circuit part.
Preferably, the main circuit part and the control circuit part are completely molded by the mold compound such that a trench is formed in a space between the control circuit terminal and the main circuit terminal.
Preferably, an impulse buffer agent is formed at the ends of the bonding wire.
To achieve another aspect of the first objective, there is provided a three dimensional power semiconductor module. The power semiconductor module includes a main circuit part mounted on an isolation substrate and including a power semiconductor device thereon; a control circuit part placed along a plane perpendicular to the main circuit part such that a control circuit device turns toward the power semiconductor device included in the main circuit part, the control circuit part including the control circuit device; a control circuit terminal placed along the same plane as the control circuit part, the control circuit terminal connected to the control circuit part; a main circuit terminal positioned along a different plane perpendicular to the main circuit part, facing the control circuit part and the control circuit terminal; a bonding wire for electrically connecting the control circuit terminal, the control circuit terminal, the power semiconductor device, and the main circuit terminal; and a mold compound for molding the main circuit part, the control circuit part, a portion of the main circuit terminal, and the entire isolation substrate, excluding its lower part, thereby conforming the module into a hexahedral shape.
Preferably, the main circuit part is bonded to the isolation substrate by an adhesive.
Preferably, an impulse buffer agent is formed at the ends of the bonding wire.
To achieve still another aspect of the first objective, there is provided a three dimensional power semiconductor module. The power semiconductor module includes a main circuit part mounted on an isolation substrate and including a power semiconductor device; a control circuit part placed along a plane perpendicular to the main circuit part such that a control circuit device turns toward the power semiconductor device in the main circuit part, the control circuit part including the control circuit device; a control circuit terminal placed along the same plane as the control circuit part and connected to the control circuit part; a main circuit terminal placed along a different plane perpendicular to the main circuit part, facing the control circuit part and the control circuit terminal; a bonding wire for electrically connecting the control circuit terminal, the control circuit device, the power semiconductor device, and the main circuit terminal, the bonding wire including an impulse buffer agent at its end; and a mold compound for molding the main circuit part, the control circuit part, a portion of the main circuit terminal, and the entire substrate, excluding its lower portion, such that a trench is formed in a space between the control circuit part and the main circuit terminal.
To achieve the second objective, there is provided a method of fabricating a three-dimensional power semiconductor module, including the steps of: (a) making a lead frame having notches in its bending regions, the lead frame including a control circuit terminal lead frame part, a control circuit lead frame part, a main circuit lead frame part, and a main circuit terminal lead frame part; (b) attaching a power semiconductor device to the main circuit lead frame part, attaching a control circuit device to the control circuit lead frame part, and performing wire bonding thereon; (c) bending the control circuit terminal lead frame part, the control circuit lead frame part, and the main circuit terminal lead frame part at the respective bending regions; (d) mounting the control circuit lead frame part on an isolation substrate, and then molding the lead frame and the isolation substrate; and (e) trimming the lead frame.
Preferably, the bending regions includes a first bending region that is a border between the main circuit lead frame part and the control circuit lead frame part; and a second bending region that is a border between the main circuit terminal lead frame part functioning as a main circuit terminal and the main circuit lead frame part, the second bending region being connected to the main circuit lead frame part.
Preferably, the step (b) further includes forming an impulse buffer agent on the metal connections of the bonding wire after the wire bonding.
Preferably, in the step (d), the control circuit lead frame part is mounted on the isolation substrate after soldering on the isolation substrate.
A semiconductor power module according to the present invention is configured such that a main circuit terminal lead frame part and a control circuit lead frame part are bent from a main circuit lead frame part, thereby reducing its size and weight, and manufacturing cost therefor. Also, a process of fabricating the power semiconductor module can be simplified. Further, it is possible to sufficiently increase the height of an isolation between an outer connection terminal and a heat sink.